`exceptions` is a stage-0 boot library as of commit
30272412, which means that building
`exceptions` in a GHC tree will generate a `dist-boot` directory.
However, this directory was not specified in `exceptions`'
`.gitignore` file, which causes it to dirty up the current `git`
working directory.
Accordingly, this bumps the `exceptions` submodule to commit
ghc/packages/exceptions@23c0b8a5,
which adds `dist-boot` to the `.gitignore` file.

As noted in #18105, previously this resulted in a rather intrusive error
message. This is in contrast to the general expectation that search
paths are merely places to look, not places that must exist.
Fixes #18105.

Instead, look through expandable unfoldings in `cprTransform`.
See the new Note [CPR for expandable unfoldings]:
```
Long static data structures (whether top-level or not) like
xs = x1 : xs1
xs1 = x2 : xs2
xs2 = x3 : xs3
should not get CPR signatures, because they
* Never get WW'd, so their CPR signature should be irrelevant after analysis
(in fact the signature might even be harmful for that reason)
* Would need to be inlined/expanded to see their constructed product
* Recording CPR on them blows up interface file sizes and is redundant with
their unfolding. In case of Nested CPR, this blow-up can be quadratic!
But we can't just stop giving DataCon application bindings the CPR property,
for example
fac 0 = 1
fac n = n * fac (n-1)
fac certainly has the CPR property and should be WW'd! But FloatOut will
transform the first clause to
lvl = 1
fac 0 = lvl
If lvl doesn't have the CPR property, fac won't either. But lvl doesn't have a
CPR signature to extrapolate into a CPR transformer ('cprTransform'). So
instead we keep on cprAnal'ing through *expandable* unfoldings for these arity
0 bindings via 'cprExpandUnfolding_maybe'.
In practice, GHC generates a lot of (nested) TyCon and KindRep bindings, one
for each data declaration. It's wasteful to attach CPR signatures to each of
them (and intractable in case of Nested CPR).
```
Fixes #18154.

Makes `interpretPackageEnv` (which loads envirinment files) a part of
`parseDynamicFlags` (parsing command-line arguments, which is typically
done once) instead of `setSessionDynFlags` (which is typically called
several times). Making several (transitive) calls to `interpretPackageEnv`,
as before, caused #18125#16318, which should be fixed now.

This implements chunks (2) and (3) of
#16762 (comment 270170). Namely,
it introduces a dedicated `HsPatSigType` AST type, which represents
the types that can appear in pattern signatures and term-level `RULE`
binders. Previously, these were represented with `LHsSigWcType`.
Although `LHsSigWcType` is isomorphic to `HsPatSigType`, the intended
semantics of the two types are slightly different, as evidenced by
the fact that they have different code paths in the renamer and
typechecker.
See also the new `Note [Pattern signature binders and scoping]` in
`GHC.Hs.Types`.

This commit updates the ghc command's man page as followings:
* Enable `man_show_urls` to show URL addresses in the `DESCRIPTION`
section of ghc.rst, because sphinx currently removes hyperlinks
for man pages.
* Add a `SEE ALSO` section to point to the GHC homepage

* Replace some non-deterministic lazy folds with
strict folds.
* Replace some O(n log n) folds in deterministic order
with O(n) non-deterministic folds.
* Replace some folds with set-operations on the underlying
IntMaps.
This reduces max residency when compiling
`nofib/spectral/simple/Main.hs` with -O0 by about 1%.
Maximum residency when compiling Cabal also seems reduced on the
order of 3-9%.

See testsuite/tests/hiefile/should_run/HieQueries.hs and
testsuite/tests/hiefile/should_run/HieQueries.stdout for an example of this
Additionally,
- Recurse into AbsBinds so that type information for pattern synonyms is saved
- Made some scopes more accurate
- Along with typeclass evidence info, also include information on Implicit
Parameters
Updates haddock submodule